The present disclosure relates generally to medical devices and, more particularly, to sensors used for sensing physiological parameters of a patient.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices may have been developed for monitoring many such physiological characteristics. Such devices may provide doctors and other healthcare personnel with information they may utilize to provide the best possible healthcare for their patients. As a result, such monitoring devices may have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. The “pulse” in pulse oximetry may refer to the time varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximeters may utilize a non-invasive sensor capable of transmitting light through a patient's tissue and that photoelectrically detects the absorption and/or scattering of the transmitted light in such tissue. Physiological characteristics may then be calculated based at least in part upon the amount of light absorbed or scattered. The light passed through the tissue may be typically selected to be of one or more wavelengths that may be absorbed or scattered by the blood in an amount correlative to the amount of the blood constituent present in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of blood constituent in the tissue using various algorithms.
To facilitate accurate and reliable measurements when monitoring physiological characteristics of a patient, a pulse oximetry sensor should be adequately in contact with the patient's tissue. When a sensor is dislodged or removed from the patient, or contact is inadequate, some or all of the emitted light does not pass through the patient's tissue, and the detected light may no longer relate in the same way to a physiological constituent. Because detected light unrelated to a physiological constituent may result in measurement inaccuracies, it may be desirable to provide a mechanism for indicating that sensor is not in sufficient contact with the patient's tissue.